Municipalities are responsible for sanitation and wastewater treatment, as stated in article 115 of the Mexican Constitution. However, in practice both federation and states share this responsibility. In studies about the Lerma-Chapala river basin, the discourse has been centered on hydric resource scarcity, often overlooking sanitation. This article studies the contribution to wastewater treatment by the National Water Commission (CNA, by its Spanish initials), for each one of the five states of the Lerma-Chapala river basin.This comparative analysis shows the diverging contributions as far as the federation is concerned, assessing their impact on each state's performance. The analysis does not reveal any significant impact, even though official statistics boast substantial achievements. These results suggest the need to analyze official data with both caution and skepticism.